Cold-cathode FEDs are known in the art. Most FEDs include at least two electrodes, one known as the emitter and another known as the extractor, accelerating electrode, or gate electrode. Additional electrodes may be formed with the FED as applications warrant. These may be known as collector, anode, or focussing elements.
An FED emitter element may take a number of geometric forms. In one prior art FED, the emitter takes the shape of a cone. In another, the emitter is formed as a wedge. Electron emission occurs primarily from the tip of the cone-shaped structure, or, correspondingly, along the edge of the wedge-shaped structure.
There are several problems associated with the fabrication of such prior art FED structures. In order to form the cones or edges of conductor materials, prior art techniques employ multiple target vapor deposition methods. Since this complex fabrication process is not easily controlled, it is not well-suited for device manufacturing. An alternative method of emitter formation includes anisotropic etching of single-crystal semiconductor material. Although the process is less complex than the previously-described process, the use of semiconductor emitter material precludes high current operation of the device.
Accordingly, there exists a need for an improved FED with an emitter structure capable of being formed by a method that avoids some of the problems of the prior art devices.